The drive for sources of low-cost, renewable and environmentally friendly power has stimulated considerable interest in solar energy and its conversion into more usable forms. The technology landscape in solar energy utilization has largely focused upon two principle technologies: 1) photovoltaic cells, in which solar radiation is directly converted into electricity, and 2) thermal utilization strategies, in which the thermal energy from substantially unfocused or minimally focused solar radiation is utilized for domestic heating purposes. Both approaches have merit, but they have yet to make a significant dent in the use of fossil fuels and other non-renewable energy sources. Photovoltaic cells remain expensive, have a limited lifetime, and offer a low quantum yield of photons into electricity. Although thermal utilization strategies have been used on a small scale for water or home heating purposes, they have yet to enjoy widespread implementation on a large scale.
A third strategy for utilizing solar energy involves receiving a focused input of solar radiation and converting the significant thermal energy therein into electricity. Such thermal conversion strategies are often referred to as concentrating solar power (CSP) techniques, in which concentrating optics provide the focused input of solar radiation to a solar collector of relatively small area. In such CSP equipment and techniques, the thermal energy received from the focused input of solar radiation is collected in a heat transfer medium and transferred to an energy-generating structure coupled to a turbine system or generator. Illustrative CSP equipment includes parabolic trough solar receivers, Fresnel or flat mirror solar receivers, and solar receiving towers.
Since very high temperatures can be generated at the location where the solar radiation is focused within CSP equipment and methods, thermally stable materials are needed for forming the heat transfer medium. Molten salts, particularly molten nitrate salts, have commonly been used for this purpose. However, molten salt heat transfer media can present a number of operational issues including, for example, corrosiveness, limited thermal stability, and engineering challenges arising from the freezing and thawing (contraction and expansion) cycles that occur following sunset and sunrise, respectively. In order to address these issues and others, relatively robust and expensive construction materials may be needed for building CSP equipment in which a molten salt heat transfer medium is used.
In view of the foregoing, improved systems and methods for concentrating thermal energy from solar radiation and obtaining power therefrom would be of significant interest in the art. The present disclosure satisfies these needs and provides related advantages as well.